hi everyone
my 2000 D2 V8 now has 141,000km on clock.
Have an issue where the exhaust keeps coming loose at the flange between the manifold and the pipe leading down to the cat's.

The gasket was replaced 10,000km ago when the motor was rebuilt, and the original OEM bolts were put back on when it was all re-assembled.

I retighten the bolts on the flange and sure enough, 2000km or so later it sounds like a chaff cutter again with a quite audible noise of exhaust from under the bonnet and a drop in performance.

Local exhaust place tells me that D2 V8's are known for cat's getting gunked up and needing replacing and the back pressure created by the blocked cat is what is causing my issue (this only happens on the passenger side).

Is this a common issue for these cars to need new cat's at around this age/km's?

Thanks
Drew